The present invention relates to organic and inorganic composite pigments, a paint using the organic and inorganic composite pigments, and a resin composition using the organic and inorganic composite pigments. More particularly, the present invention relates to organic and inorganic composite pigments not only being lessened in amount of organic pigments desorbed from the surface of the white inorganic particles, but also exhibiting an excellent light resistance owing to good ultraviolet absorbing property thereof, a paint using such organic and inorganic composite pigments, and a resin composition using such organic and inorganic composite pigments.
As well known in the art, inorganic pigments and organic pigments have been used as color pigments for resins, paints, printing inks or the like according to the applications.
In general, it is known that the inorganic pigments have an excellent light resistance, but are have a low tinting strength and fail to show a clear hue. There have been known some inorganic pigments capable of exhibiting a clear hue. However, many of these inorganic pigments having a clear hue contain as constituents thereof, harmful metals such as lead, mercury, cadmium, chromium or the like. Therefore, it has been strongly required to provide alternate harmless pigments exhibiting a more clear hue instead of such inorganic pigments from the standpoints of hygiene, safety and environmental protection.
On the other hand, it is known that the organic pigments exhibit a clear hue, but have low hiding power and are deteriorated in light resistance.
In addition, various pigments as described above have been frequently used in outdoor applications and, therefore, required to maintain a good hue thereof for a long period of time. Also, it is necessary that the pigments have a good light resistance, in particular, are free from discoloration by ultraviolet light.
Thus, it has been required to provide pigments exhibiting not only a clear hue, but also excellent tinting strength and light resistance.
Hitherto, in order to obtain pigments having excellent properties required for color pigments, it has been attempted to use the inorganic pigments in combination with the organic pigments. For example, there have been proposed a method of co-precipitating chrome yellow and phthalocyanine blue together; a method of adhering the organic pigments onto the surface of the inorganic pigments; or the like (Japanese Patent Application Laid-Open (KOKAI) Nos. 4-132770 (1992) and 11-181329 (1999), etc.). Further, there have been known particles exhibiting an excellent ultraviolet-absorbing property, which contain ultraviolet light-absorbing compounds (Japanese Patent Application Laid-Open (KOKAI) Nos. 11-222421 (1999) and 2000-80021, etc.).
At present, it has been strongly required to provide composite pigments not only being lessened in amount of organic pigments desorbed from the surface of white inorganic particles, but also exhibiting an excellent light resistance. However, conventional composite pigments have failed to satisfy these properties.
That is, in the case of the composite pigments obtained by co-precipitating chrome yellow and phthalocyanine blue together, the chrome yellow used therein has a toxicity, and a paint obtained using such composite pigments is deteriorated in storage stability owing to the co-precipitation production method. Further, a coating film obtained from the paint tends to suffer from color-floating in some cases.
In the method described in Japanese Patent Application Laid-Open (KOKAI) No. 4-132770 (1992), since the organic pigments are precipitated in the presence of the inorganic pigments, the adhesion of the organic pigments onto the inorganic pigments is insufficient.
In the method described in Japanese Patent Application Laid-Open (KOKAI) No. 11-181329 (1999), after the organic pigments are added to a solution prepared by dissolving organopolysiloxane in cyclic silicone solution, so as to be subjected to fine particle treatment, the obtained particles are adhered to high-oil absorption inorganic pigments, and then the cyclic silicone is volatilized therefrom. Therefore, the adhesion of the organic pigments onto the inorganic pigments is insufficient.
In Japanese Patent Application Laid-Open (KOKAI) No. 11-222421 (1999), it is described that an ultraviolet light-absorbing compound is bonded onto the surface of inorganic particles through a coupling agent. The object of the invention of this KOKAI is to provide an ultraviolet light-protecting agent having a good transparency, but not to provide composite pigments having a clear hue.
In Japanese Patent Application Laid-Open (KOKAI) No. 2000-80021, it is described that a liquid organic ultraviolet light-absorbing compound is coated onto inorganic pigments through an organic high-molecular compound. However, since the pigments are obtained by coat-treating inorganic particles, nylon powder or spherical silicone resin particles with the liquid organic ultraviolet light-absorbing compound, the obtained particles fail to show a clear hue.
Further, in Japanese Patent Application Laid-Open (KOKAI) No. 11-323174 (1999), there are described iron-based black composite particles comprising black iron oxide particles or black iron oxide hydroxide particles as core particles; a coating formed on the surface of the core particle, comprising organosilane compounds obtainable from alkoxysilanes; and a carbon black coat formed on the coating layer composed of the organosilane compounds. However, this KOKAI is directed to the technique for fixedly adhering carbon black onto the core particle and, therefore, the technical sphere of this KOKAI is quite different from that for obtaining pigments having a high chroma and exhibiting a more excellent light resistance, in particular, being free from dicolorationby ultraviolet light.
As a result of the present inventors"" earnest studies for solving the above problems, it has been found that by forming an organic pigment coat onto the surface of white inorganic particles through a coating composed of organosilane compounds obtainable from alkoxysilanes, or polysiloxanes, and allowing an ultraviolet light-absorbing agent to exist in any portion from the surface of the white inorganic particle to the surface of the organic pigment coat (including such a case where the ultraviolet light-absorbing agent is adhered onto the organic pigment coat), the obtained organic and inorganic composite particles not only exhibit an excellent clear hue and an excellent light resistance, but also contain no harmful elements. The present invention has been attained on the basis of the above finding.
An object of the present invention is to provide organic and inorganic composite pigments being lessened in amount of organic pigments desorbed from the surface of the white inorganic particles, exhibiting an excellent clear hue and an excellent light resistance, and containing no harmful elements.
To accomplish with the aim, in a first aspect of the present invention, there are provided organic and inorganic composite pigments having an average particle diameter of 0.01 to 10.0 xcexcm, comprising:
white inorganic particles;
a coating formed on surface of said white inorganic particle, comprising organosilane compounds obtainable from alkoxysilanes, or polysiloxanes;
an organic pigment coat formed on said coating in an amount of 1 to 200 parts by weight based on 100 parts by weight of the white inorganic particles; and
an ultraviolet light-absorbing agent existing in at least a part of any portion from the surface of said white inorganic particle to surface of said organic pigment coat.
In a second aspect of the present invention, there are provided organic and inorganic composite pigments having an average particle diameter of 0.01 to 10.0 xcexcm, comprising:
white inorganic particles;
a coating layer formed on surface of said white inorganic particle, comprising at least one compound selected from the group consisting of hydroxides of aluminum, oxides of aluminum, hydroxides of silicon and oxides of silicon;
a coating formed said coating layer, comprising organosilane compounds obtainable from alkoxysilanes, or polysiloxanes;
an organic pigment coat formed on said coating in an amount of 1 to 200 parts by weight based on 100 parts by weight of the white inorganic particles; and
an ultraviolet light-absorbing agent existing in at least a part of any portion from the surface of said white inorganic particle to surface of said organic pigment coat.
In a third aspect of the present invention, there are provided organic and inorganic composite pigments having an average particle diameter of 0.01 to 10.0 xcexcm, comprising:
white inorganic particles;
a coating formed on surface of said white inorganic particle, comprising organosilane compounds obtainable from alkoxysilanes, or polysiloxanes;
an organic pigment coat formed on said coating in an amount of 1 to 200 parts by weight based on 100 parts by weight of the white inorganic particles; and
an ultraviolet light-absorbing agent existing in at least a part of a portion selected from the group consisting of (1) a portion between the surface of the white inorganic particle and the coating comprising organosilane compounds obtainable from alkoxysilanes, or polysiloxanes; (2) an inside portion of the coating comprising organosilane compounds obtainable from alkoxysilanes, or polysiloxanes; (3) a portion between the coating comprising organosilane compounds obtainable from alkoxysilanes, or polysiloxanes, and the organic pigment coat; (4) an inside portion of the organic pigment coat formed onto the coating comprising organosilane compounds obtainable from alkoxysilanes, or polysiloxanes; and (5) a portion on surface of the organic pigment coat.
In a fourth aspect of the present invention, there are provided organic and inorganic composite pigments having an average particle diameter of 0.01 to 10.0 xcexcm, a BET specific surface area value of 1.0 to 100 m2/g and a light resistance (xcex94E* value) of not more than 3.5, comprising:
white inorganic particles;
a coating formed on surface of said white inorganic particle, comprising organosilane compounds obtainable from alkoxysilanes, or polysiloxanes;
an organic pigment coat formed on said coating in an amount of 1 to 200 parts by weight based on 100 parts by weight of the white inorganic particles; and
an ultraviolet light-absorbing agent existing in at least a part of any portion from the surface of said white inorganic particle to surface of said organic pigment coat.
In a fifth aspect of the present invention, there is provided a paint comprising:
said organic and inorganic composite pigments defined in any one of the first aspect to fourth aspect; and
a paint base material.
In a sixth aspect of the present invention, there is provided a rubber or resin composition comprising:
said organic and inorganic composite pigments defined in any one of the first aspect to fourth aspect; and
a base material for rubber or resin composition.
The present invention will now be described in detail below.
First, the organic and inorganic composite pigments according to the present invention are described.
As the white inorganic particles, there may be used white pigments such as titanium dioxide and zinc oxide; pearl pigments such as titanium mica and muscovite; and extender pigments such as clay, calcium carbonate, precipitated barium sulfate, alumina white, white carbon and talc. The white inorganic particles may be appropriately selected from the above-described pigments depending properties required therefor or applications thereof, for example, the white pigments are preferably used in applications requiring a hiding power, the pearl pigments are preferably used in applications requiring pearl-like gloss, and the extender pigments are preferably used in applications requiring a transparency.
The white inorganic particles may be those particles having any suitable shape such as spherical particles, granular particles, polyhedral particles, acicular particles, spindle-shaped particles, rice ball-shaped particles, flake-shaped particles, scale-shaped particles and plate-shaped particles.
The white inorganic particles have an average particle diameter of usually 0.009 to 9.95 xcexcm, preferably 0.025 to 9.45 xcexcm, more preferably 0.045 to 8.95 xcexcm.
When the average particle diameter of the white inorganic particles is more than 9.95 xcexcm, the obtained organic and inorganic composite pigments may become coarse, resulting in deteriorated tinting strength. When the average particle diameter of the white inorganic particles is less than 0.009 xcexcm, such particles may tend to be agglomerated due to fine particles. As a result, it may be difficult to adhere the ultraviolet light-absorbing agent onto the surface of the white inorganic particles, to form a uniform coating comprising the organosilane compounds obtainable from alkoxysilanes, or polysiloxanes on the surface of the white inorganic particles, and to uniformly adhere the organic pigments onto the surface of the coating layer.
The white inorganic particles have a BET specific surface area value of preferably not less than 0.5 m2/g. When the BET specific surface area value is less than 0.5 m2/g, the white inorganic particles may become coarse, so that the obtained organic and inorganic composite pigments may also become coarse and, therefore, may tend to be deteriorated in tinting strength. In the consideration of a good tinting strength of the obtained organic and inorganic composite pigments, the BET specific surface area value of the white inorganic particles is more preferably not less than 1.0 m2/g, still more preferably not less than 1.5 m2/g. In the consideration of adhering the ultraviolet light-absorbing agent onto the surface of the white inorganic particles, forming a uniform coating comprising the organosilane compounds obtainable from alkoxysilanes or polysiloxanes on the surface of the white inorganic particles, or uniformly forming the organic pigments coat onto the surface of the coating layer, the upper limit of the BET specific surface area value of the white inorganic particles is preferably 95 m2/g, more preferably 90 m2/g, still more preferably 85 m2/g.
As to the hue of the white inorganic particles, the L* value thereof is preferably not less than 70.00, more preferably not less than 75.00; and the C* value thereof is preferably not more than 18.00, more preferably not more than 16.00. When the L* and C* values of the white inorganic particles are out of the above-specified ranges, the white inorganic particles fail to show a white color, so that it may be difficult to obtain the aimed organic and inorganic composite pigments exhibiting a clear hue.
As to the hiding power of the white inorganic particles used in the present invention, the white pigments have a hiding power of preferably not less than 600 cm2/g; and the pearl pigments and extender pigments have a hiding power of less than 600 cm2/g when measured by the below-mentioned evaluation method.
As to the light resistance of the white inorganic particles, the xcex94E* value thereof is preferably not more than 12.0, more preferably not more than 11.0, still more preferably not more than 10.0 when measured by the below-mentioned evaluation method. The lower limit of the light resistance (xcex94E* value) of the white inorganic particles is usually about 4.0 or slightly higher.
As organosilicon compounds (gluing agents) used in the present invention, at least one organosilicon compound selected from the group consisting of (1) organosilane compounds obtained from alkoxysilane compounds; and (2) polysiloxanes, or modified polysiloxanes selected from the group consisting of (2-A) polysiloxanes modified with at least one compound selected from the group consisting of polyethers, polyesters and epoxy compounds (hereinafter referred to merely as xe2x80x9cmodified polysiloxanesxe2x80x9d), and (2-B) polysiloxanes whose molecular terminal is modified with at least one group selected from the group consisting of carboxylic acid groups, alcohol groups and a hydroxyl group (hereinafter referred to merely as xe2x80x9cterminal-modified polysiloxanesxe2x80x9d).
The organosilane compounds (1) can be produced from alkoxysilane compounds represented by the formula (I):
R1aSiX4xe2x88x92axe2x80x83xe2x80x83(I)
wherein R1 is C6H5xe2x80x94, (CH3)2CHCH2xe2x80x94 or n-CbH2b+1xe2x80x94 (wherein b is an integer of 1 to 18); X is CH3Oxe2x80x94 or C2H5Oxe2x80x94; and a is an integer of 0 to 3.
Specific examples of the alkoxysilane compounds may include methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethyoxysilane, diphenyldiethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane or the like. Among these alkoxysilane compounds, in view of the degree of desorption and the adhering effect of the organic pigments, methyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane and isobutyltrimethoxysilane, phenyltriethyoxysilane are preferred, and methyltriethoxysilane and methyltrimethoxysilane are more preferred.
As the polysiloxanes (2), there may be used those compounds represented by the formula (II): 
wherein R2 is Hxe2x80x94 or CH3xe2x80x94, and d is an integer of 15 to 450.
As the modified polysiloxanes (2-A), there may be used:
(a1) polysiloxanes modified with polyethers represented by the formula (III): 
xe2x80x83wherein R3 is xe2x80x94(xe2x80x94CH2xe2x80x94)hxe2x80x94; R4 is xe2x80x94(xe2x80x94CH2xe2x80x94)ixe2x80x94CH3; R5 is xe2x80x94OH, xe2x80x94COOH, xe2x80x94CHxe2x95x90CH2, xe2x80x94CH(CH3)xe2x95x90CH2 or xe2x80x94(xe2x80x94CH2xe2x80x94)jxe2x80x94CH3; R6 is xe2x80x94(xe2x80x94CH2xe2x80x94)kxe2x80x94CH3; g and h are an integer of 1 to 15; i, j and k are an integer of 0 to 15; e is an integer of 1 to 50; and f is an integer of 1 to 300;
(a2) polysiloxanes modified with polyesters represented by the formula (IV): 
xe2x80x83wherein R7, R8 and R9 are xe2x80x94(xe2x80x94CH2xe2x80x94)qxe2x80x94 and may be the same or different; R10 is xe2x80x94OH, xe2x80x94COOH, xe2x80x94CHxe2x95x90CH2, xe2x80x94CH(CH3)xe2x95x90CH2 or xe2x80x94(xe2x80x94CH2xe2x80x94)rxe2x80x94CH3; R11 is xe2x80x94(xe2x80x94CH2xe2x80x94)sxe2x80x94CH3; n and q are an integer of 1 to 15; r and s are an integer of 0 to 15; exe2x80x2 is an integer of 1 to 50; and fxe2x80x2 is an integer of 1 to 300;
(a3) polysiloxanes modified with epoxy compounds represented by the formula (V): 
xe2x80x83wherein R12 is xe2x80x94(xe2x80x94CH2xe2x80x94)vxe2x80x94; v is an integer of 1 to 15; t is an integer of 1 to 50; and u is an integer of 1 to 300; or a mixture thereof.
As the terminal-modified polysiloxanes (2-B), there may be used those represented by the formula (VI): 
wherein R13 and R14 are xe2x80x94OH, R16OH or R17COOH and may be the same or different; R15 is xe2x80x94CH3 or xe2x80x94C6H5; R16 and R17 are xe2x80x94(xe2x80x94CH2xe2x80x94)yxe2x80x94; wherein y is an integer of 1 to 15; w is an integer of 1 to 200; and x is an integer of 0 to 100.
In view of the desorption percentage and the adhering effect of the organic pigment, polysiloxanes having methyl hydrogen siloxane units, the polysiloxanes modified with the polyethers and the polysiloxanes whose terminals are modified with carboxylic acid groups are preferred.
The amount of the coating layer composed of the organosilane compounds obtained from alkoxysilane compounds, or polysiloxanes is preferably 0.01 to 15.0% by weight, more preferably 0.02 to 12.5% by weight, still more preferably 0.03 to 10.0% by weight (calculated as C) based on the weight of the gluing agent-coated white inorganic particles coated with the organosilane compounds or polysiloxanes.
When the amount of the coating layer composed of the organosilane compounds or polysiloxanes is less than 0.01% by weight, it may be difficult to coat and/or adhere not less than one part by weight of the organic pigment onto 100 parts by weight of the white inorganic particles. When the amount of the coating layer composed of the organosilane compounds or polysiloxanes is more than 15.0% by weight, since it is possible to coat and/or adhere 1 to 200 parts by weight of the organic pigment onto 100 parts by weight of the white inorganic particles therethrough, it is unnecessary to form the coating layer composed of the organosilane compounds or polysiloxanes in an amount of more than 15.0% by weight.
As the organic pigments used in the present invention, there may be exemplified various organic pigments ordinarily used as colorants for paints and resin compositions such as organic red-based pigments, organic blue-based pigments, organic yellow-based pigments, organic green-based pigments, or the like.
Examples of the organic red-based pigments may include quinacridon pigments such as quinacridon red, azo-based pigments such as permanent red, condensed azo pigments such as condensed azo red, perylene pigments such as perylene red, or the like. Examples of the organic blue-based pigments may include phthalocyanine-based pigments such as metal-free phthalocyanine blue, phthalocyanine blue and fast sky blue, alkali blue, or the like. Examples of the organic yellow-based pigments may include monoazo-based pigments such as Hanza yellow, disazo-based pigments such as benzidine yellow and permanent yellow, condensed azo pigments such as condensed azo yellow, or the like. Examples of the organic green-based pigments may include phthalocyanine-based pigments such as phthalocyanine green, or the like.
Meanwhile, various organic pigments as described above may be used in the form of a mixture of any two or more thereof according to the hue required.
The amount of the organic pigments adhered in the form of the coating layer is usually 1 to 200 parts by weight based on 100 parts by weight of the white inorganic particles.
When the amount of the organic pigments coat is less than 1 part by weight or more than 200 parts by weight, it may be difficult to obtain the aimed organic and inorganic composite pigments. The amount of the organic pigments adhered in the form of the coating layer is preferably 1 to 175 parts by weight, more preferably 1 to 150 parts by weight.
Examples of the ultraviolet light-absorbing agent used in the present invention may include benzotriazole-based ultraviolet light-absorbing agents, benzophenone-based ultraviolet light-absorbing agents and salicylate-based ultraviolet light-absorbing agents. Specific examples of the benzotriazole-based ultraviolet light-absorbing agents may include hydroxyphenylbenzotriazole derivatives, methyl-3-(3-t-butyl-5-(2H-benzotriazole-2-yl)-4-hydroxyphenyl)propionate-polyethylene glycol, 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2-(2-hydroxy-3,5-bis(xcex1,xcex1-dimethylbenzyl)phenyl)-2H-benzotriazole, 2-(3,5-di-t-butyl-2-hydroxyphenyl)benzotriazole, 2-(3-t-butyl-5-methyl-2-hydroxyphenyl)-5-chlororbenzotriazole, 2-(3,5-di-t-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole, 2-(2xe2x80x2-hydroxy-5-t-octylphenyl)benzotriazole or the like. Specific examples of the benzophenone-based ultraviolet light-absorbing agents may include 2-hydroxy-4-methoxybenzophenone, 2,2xe2x80x2-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4xe2x80x2-chlorobenzophenone, 2,2xe2x80x2-dihydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2,4-dihydroxybenzophenone, 2,4-dibenzoyl-resorcinol, resorcinol monobenzoate, 5-chloro-2-hydroxybenzophenone, 2,2xe2x80x2-dihydroxy-4,4xe2x80x2-dimethoxybenzophenone, 4-dodecyl-2-hydroxybenzophenone, 2,2xe2x80x2, 4,4xe2x80x2-tetrahydroxybenzophenone or the like. Specific examples of the salicylate-based ultraviolet light-absorbing agents may include phenyl salicylate, 4-t-butyl-phenyl salicylate, p-octyl-phenyl salicylate or the like. In the consideration of good light resistance of the obtained organic and inorganic composite pigments, the benzotriazole-based ultraviolet light-absorbing agents are preferred, and further in the consideration of formation of more uniform coating layer, liquid ultraviolet light-absorbing agents such as hydroxyphenylbenzotriazole derivatives, methyl-3-(3-t-butyl-5-(2H-benzotriazole-2-yl)-4-hydroxyphenyl)propionate-polyethylene glycol and the like are preferred.
The amount of the ultraviolet light-absorbing agent existing in the organic and inorganic composite pigments is preferably 0.1 to 20% by weight, more preferably 0.1 to 18% by weight, still more preferably 0.1 to 15% by weight based on the weight of the organic pigments coated.
When the amount of the ultraviolet light-absorbing agent existing in the organic and inorganic composite pigments is less than 0.1% by weight, the obtained organic and inorganic composite pigments may tend to be deteriorated in light resistance. When the amount of the ultraviolet light-absorbing agent existing in the organic and inorganic composite pigments is more than 20% by weight, the effect of improving the light resistance is already saturated. Therefore, it is unnecessary and meaningless to make the ultraviolet light-absorbing agent exist in the organic and inorganic composite pigments in such a large amount.
The ultraviolet light-absorbing agent may exist in any suitable portion of the organic and inorganic composite pigments to impart a good ultraviolet light-absorbing property thereto. More specifically, the ultraviolet light-absorbing agent may exist in at least a part of any portion selected from the group consisting of (1) a portion between the surface of the white inorganic particle and the coating comprising organosilane compounds obtainable from alkoxysilanes, or polysiloxanes as a coating layer; (2) an inside portion of the coating comprising organosilane compounds obtainable from alkoxysilanes, or polysiloxanes; (3) a portion between the coating formed on the surface of the white inorganic particle, comprising organosilane compounds obtainable from alkoxysilanes, or polysiloxanes, and the organic pigment coat as a coating layer; (4) an inside portion of the organic pigment coat adhered onto the coating comprising organosilane compounds obtainable from alkoxysilanes, or polysiloxanes; and (5) a portion on the surface of the organic pigment coat as a coating layer, i.e., on the surface of the composite particle. Preferably, the ultraviolet light-absorbing agent may be present in either (4) or (5).
In the above-mentioned embodiment (1), the ultraviolet light-absorbing agent may exist on at least a part of the surface of the white inorganic particle as a coating layer; in the above-mentioned embodiment (3), the ultraviolet light-absorbing agent may exist on at least a part of the surface of the coating comprising organosilane compounds obtainable from alkoxysilanes, or polysiloxanes as a coating layer, and in the above-mentioned embodiment (5), the ultraviolet light-absorbing agent may exist on at least a part of the surface of the organic pigment coat as a coating layer.
The particle shape and particle size of the organic and inorganic composite pigments according to the present invention may largely depend upon those of the white inorganic particles as core particles. Specifically, the organic and inorganic composite pigments may have a particle configuration similar to that of the core particles.
More specifically, the organic and inorganic composite pigments of the present invention have an average particle diameter of usually 0.01 to 10.0 xcexcm, preferably 0.03 to 9.5 xcexcm more preferably 0.05 to 9.0 xcexcm.
When the average particle diameter of the organic and inorganic composite pigments is more than 10.0 xcexcm, the particle size thereof is too large, resulting in deteriorated tinting strength. When the average particle diameter of the organic and inorganic composite pigments is less than 0.01 xcexcm, such organic and inorganic composite pigments tend to be agglomerated together due to fine particles, so that it may become difficult to disperse the organic and inorganic composite pigments in paint vehicles or resin compositions.
The organic and inorganic composite pigments of the present invention have a BET specific surface area value of preferably 1.0 to 100 m2/g, more preferably 1.5 to 95 m2/g, still more preferably 2.0 to 90 m2/g. When the BET specific surface area value is less than 1.0 m2/g, the obtained organic and inorganic composite pigments may become coarse, resulting in deteriorated tinting strength. When the BET specific surface area value is more than 100 m2/g, the organic and inorganic composite pigments tend to be agglomerated together due to fine particles, so that it may be difficult to disperse the organic and inorganic composite pigments in paint vehicles or resin compositions.
The organic and inorganic composite pigments of the present invention have a tinting strength of preferably not less than 115%, more preferably not less than 120% when measured by the below-mentioned evaluation method.
The hiding power of the organic and inorganic composite pigments produced by using white pigments as the white inorganic particles is preferably not less than 600 cm2/g, more preferably not less than 700 cm2/g when measured by the below-mentioned evaluation method. Also, the hiding power of the organic and inorganic composite pigments produced by using extender pigments or pearl pigments as the white inorganic particles is preferably less than 600 cm2/g, more preferably not more than 500 cm2/g when measured by the below-mentioned evaluation method.
As to the light resistance of the organic and inorganic composite pigments of the present invention, the xcex94E* value thereof is preferably not more than 3.5, more preferably not more than 3.0 when measured by the below-mentioned evaluation method.
The degree of desorption of organic pigments from the organic and inorganic composite pigments is preferably rank 4 or rank 5, more preferably rank 5. When the degree of desorption of organic pigments from the organic and inorganic composite pigments is rank 1, 2 or 3, the organic and inorganic composite pigments may tend to be inhibited from being uniformly dispersed in paint vehicles or resin compositions, because of the desorbed organic pigments. Further, since the hue of the white inorganic particles is exposed to the surface of the composite particles at the portion from which the organic pigments are desorbed, it may be difficult to obtain organic and inorganic composite pigments having a uniform hue.
In the organic and inorganic composite particles according to the present invention, if required, the surface of the core particle may be previously coated with at least one compound selected from the group consisting of hydroxides of aluminum, oxides of aluminum, hydroxides of silicon and oxides of silicon. The organic and inorganic composite particles using the core particles having such a coat composed of at least one compound selected from the group consisting of hydroxides of aluminum, oxides of aluminum, hydroxides of silicon and oxides of silicon (hereinafter referred to merely as xe2x80x9cintermediate coatxe2x80x9d), can be more effectively reduced in amount of organic pigments desorbed from the surface of the composite particles as compared to those using the core particles having no intermediate coat.
The amount of the intermediate coat is preferably 0.01 to 20% by weight (calculated as Al, SiO2 or a sum of Al and SiO2) based on the weight of the core particles having the intermediate coat.
When the amount of the intermediate coat is less than 0.01% by weight, it may be difficult to attain the improved effect of reducing the amount of organic pigments desorbed. As long as the amount of the intermediate coat is in the range of 0.01 to 20% by weight, the improved effect of reducing the amount of organic pigments desorbed can be sufficiently attained. Therefore, it is unnecessary to form the intermediate coat in an amount of more than 20% by weight.
The organic and inorganic composite pigments produced by using the white inorganic particles coated with at least one compound selected from the group consisting of hydroxides of aluminum, oxides of aluminum, hydroxides of silicon and oxides of silicon according to the present invention is substantially the same in particle size, BET specific surface area value, hue (L*, a* and b* values), tinting strength and hiding power as those of the organic and inorganic composite pigments produced by using the white inorganic particles uncoated with at least one compound selected from the group consisting of hydroxides of aluminum, oxides of aluminum, hydroxides of silicon and oxides of silicon according to the present invention. The degree of desorption of the organic pigments from the organic and inorganic composite pigments can be improved by coating the surface of the white inorganic particles with at least one compound selected from the group consisting of hydroxides of aluminum, oxides of aluminum, hydroxides of silicon and oxides of silicon, so that the obtained organic and inorganic composite pigments can show a degree of desorption of the organic pigments of preferably the rank 5, and a light resistance (xcex94E* value) of preferably not more than 3.0, more preferably not more than 2.5.
Next, the paint containing the organic and inorganic composite pigments of the present invention is described.
The solvent-based paint containing the organic and inorganic composite pigments of the present invention has such a storage stability that the xcex94E* value thereof is preferably not more than 1.5, more preferably not more than 1.2. When the paint is formed into a coating film, the gloss of the coating film is preferably 75 to 110%, more preferably 80 to 110%. As to the light resistance of the coating film, the xcex94E* value thereof is preferably not more than 3.5, more preferably not more than 3.0. In the case where extender pigments or pearl pigments are used as the white inorganic particles, the coating film has such a transparency that the linear absorption thereof is preferably not more than 0.10 xcexcmxe2x88x921, more preferably not more than 0.09 xcexcmxe2x88x921.
The solvent-based paint containing the organic and inorganic composite pigments coated with at least one compound selected from the group consisting of hydroxides of aluminum, oxides of aluminum, hydroxides of silicon and oxides of silicon, of the present invention has such a storage stability that the xcex94E* value thereof is preferably not more than 1.5, more preferably not more than 1.2. When the paint is formed into a coating film, the gloss of the coating film is preferably 80 to 115%, more preferably 85 to 115%. As to the light resistance of the coating film, the xcex94E* value thereof is preferably not more than 3.0, more preferably not more than 2.5. In the case where extender pigments or pearl pigments are used as the white inorganic particles, the coating film has such a transparency that the linear absorption thereof is preferably not more than 0.10 xcexcmxe2x88x921, more preferably not more than 0.09 xcexcmxe2x88x921.
The water-based paint containing the organic and inorganic composite pigments of the present invention has such a storage stability that the xcex94E* value thereof is preferably not more than 1.5, more preferably not more than 1.2. When the paint is formed into a coating film, the gloss of the coating film is preferably 70 to 110%, more preferably 75 to 110%. As to the light resistance of the coating film, the xcex94E* value thereof is preferably not more than 3.5, more preferably not more than 3.0. In the case where extender pigments or pearl pigments are used as the white inorganic particles, the coating film has such a transparency that the linear absorption thereof is preferably not more than 0.11 xcexcmxe2x88x921, more preferably not more than 0.10 xcexcmxe2x88x921.
The water-based paint containing the organic and inorganic composite pigments coated with at least one compound selected from the group consisting of hydroxides of aluminum, oxides of aluminum, hydroxides of silicon and oxides of silicon, of the present invention has such a storage stability that the xcex94E* value thereof is preferably not more than 1.5, more preferably not more than 1.2. When the paint is formed into a coating film, the gloss of the coating film is preferably 75 to 115%, more preferably 80 to 115%. As to the light resistance of the coating film, the xcex94E* value thereof is preferably not more than 3.0, more preferably not more than 2.5. In the case where extender pigments or pearl pigments are used as the white inorganic particles, the coating film has such a transparency that the linear absorption thereof is preferably not more than 0.11 xcexcmxe2x88x921, more preferably not more than 0.10 xcexcmxe2x88x921.
The amount of the organic and inorganic composite particles blended in the paint according to the present invention is in the range of usually 0.5 to 100 parts by weight based on 100 parts by weight of a paint base material. In the consideration of handling of the paint, the amount of the organic and inorganic composite particles blended in the paint is preferably 1.0 to 100 parts by weight, more preferably 2.0 to 100 parts by weight based on 100 parts by weight of the paint base material.
The paint base material comprises a resin and a solvent, and may further contain, if required, a defoamer, an extender pigment, a drying agent, a surfactant, a hardening accelerator, an assistant, or the like.
Examples of the resin used in the paint base material may include resins ordinarily used for solvent-based paints such as acrylic resins, alkyd resins, polyester resins, polyurethane resins, epoxy resins, phenol resins, melamine resins, amino resins, or the like. Examples of the resins used in the paint base material for water-based paints may include resins ordinarily used for water-based paints such as water-soluble alkyd resins, water-soluble melamine resins, water-soluble acrylic resins, water-soluble urethane emulsion resins, or the like.
As the solvent for solvent-based paints, there may be exemplified those solvents ordinarily used for solvent-based paints such as toluene, xylene, thinner, methyl isobutyl ketone, glycol ether-based solvents such as ethyl cellosolve and butyl cellosolve, alcohol-based solvents such as butyl alcohol, aliphatic hydrocarbon-based solvents such as hexane, or the like.
As the solvents for water-based paints, there may be used a mixture of water and a water-soluble organic solvent ordinarily used for water-based paints such as glycol ether-based solvents such as butyl cellosolve, alcohol-based solvents such as butyl alcohol, or the like
As the defoamer, there may be used commercially available products such as xe2x80x9cNOPCO 8034 (tradename)xe2x80x9d, xe2x80x9cSN DEFOAMER 477 (tradename)xe2x80x9d, xe2x80x9cSN DEFOAMER 5013 (tradename)xe2x80x9d, xe2x80x9cSN DEFOAMER 247 (tradename)xe2x80x9d and xe2x80x9cSN DEFOAMER 382. (tradename)xe2x80x9d (all produced by SUN NOPCO CO., LTD.), xe2x80x9cANTI-FOAM 08 (tradename)xe2x80x9d and xe2x80x9cEMARGEN 903 (tradename)xe2x80x9d (both produced by KAO CO., LTD.), or the like.
Next, the resin composition colored with the organic and inorganic composite pigments of the present invention is described.
The resin composition colored with the organic and inorganic composite pigments of the present invention exhibits a dispersibility of preferably rank 4 or 5, more preferably rank 5 when visually observed by the below-mentioned evaluation method, and a light resistance (xcex94E* value) of preferably not more than 3.5, more preferably not more than 3.0. Meanwhile, when extender pigments or pearl pigments are used as the white inorganic particles, the resin composition has such a transparency that the linear absorption thereof is preferably not more than 0.10 xcexcmxe2x88x921, more preferably not more than 0.09 xcexcmxe2x88x921.
The resin composition colored with the organic and inorganic composite pigments coated with at least one compound selected from the group consisting of hydroxides of aluminum, oxides of aluminum, hydroxides of silicon and oxides of silicon, of the present invention exhibits a dispersibility of preferably rank 4 or 5, more preferably rank 5 when visually observed by the below-mentioned evaluation method, and a light resistance (xcex94E* value) of preferably not more than 3.0, more preferably not more than 2.5. Meanwhile, when extender pigments or pearl pigments are used as the white inorganic particles, the resin composition has such a transparency that the linear absorption thereof is preferably not more than 0.10 xcexcmxe2x88x921, more preferably not more than 0.09 xcexcmxe2x88x921.
The amount of the organic and inorganic composite particles blended in the resin composition according to the present invention is usually in the range of 0.01 to 200 parts by weight based on 100 parts by weight of the resin. In the consideration of handling of the resin composition, the amount of the organic and inorganic composite particles blended therein is preferably 0.05 to 150 parts by weight, more preferably 0.1 to 100 parts by weight based on 100 parts by weight of the resin.
The base material of the resin composition according to the present invention comprises the organic and inorganic composite particles and known thermoplastic resins, and may further contain, if required, additives such as lubricants, plasticizers, antioxidants, ultraviolet light absorbers, various stabilizers or the like.
As the reins, there may be used natural rubbers; synthetic rubbers; thermoplastic resins, e.g., polyolefins such as polyethylene, polypropylene, polybutene and polyisobutylene, polyvinyl chloride, styrene polymers or polyamides, or the like.
The additives may be added in an amount of usually not more than 50% by weight based on the total amount of the organic and inorganic composite particles and the resin. When the amount of the additives added is more than 50% by weight, the obtained resin composition may be deteriorated in moldability.
The resin composition is produced by previously intimately mixing the raw resin material with the organic and inorganic composite particles, and then kneading the resultant mixture using a kneader or an extruder under heating while applying a strong shear force thereto in order to deaggregate the agglomerated organic and inorganic composite particles, and uniformly disperse the organic and inorganic composite particles in the resin. Then, the obtained resin composition is molded into an aimed shape upon use.
Next, the process for producing the organic and inorganic composite pigments of the present invention is described.
The organic and inorganic composite pigments of the present invention can be produced by conducting essential steps of (i) mixing white inorganic particles with alkoxysilanes or polysiloxanes to form a coating comprising alkoxysilanes or polysiloxanes on the surface of the white inorganic particle; and (ii) then mixing the white inorganic particles coated with alkoxysilanes or polysiloxanes thereon with organic pigments to form an organic pigment coat on the coating layer composed of alkoxysilanes or polysiloxanes, in combination with a step of incorporating an ultraviolet light-absorbing agent in any suitable portion of the organic and inorganic composite pigments.
More specifically, the organic and inorganic composite pigments can be produced by any of the following methods (1) to (5):
(1) Method of preliminarily mixing the white inorganic particles with the ultraviolet light-absorbing agent to adhere the ultraviolet light-absorbing agent onto the surface of the white inorganic particle; successively mixing alkoxysilanes or polysiloxanes with white inorganic particles adhered with the ultraviolet light-absorbing agent to form a coating comprising alkoxysilanes or polysiloxanes on the surface of the white inorganic particle adhered with the ultraviolet light-absorbing agent; and then mixing organic pigments with the white inorganic particles coated with alkoxysilanes or polysiloxanes to form an organic pigment coat on the coating layer composed of alkoxysilanes or polysiloxanes.
(2) Method of preliminarily mixing alkoxysilanes or polysiloxanes with the ultraviolet light-absorbing agent to prepare a mixture thereof; mixing white inorganic particles with the resultant mixture to form a coating composed of the mixture of the alkoxysilanes or polysiloxanes and the ultraviolet light-absorbing agent on the surface of the white inorganic particle; and then mixing the thus obtained particles with organic pigments to form an organic pigment coat on the coating composed of the mixture.
(3) Method of mixing white inorganic particles with alkoxysilanes or polysiloxanes to form a coating composed of alkoxysilanes or polysiloxanes on the surface of the white inorganic particle; mixing the ultraviolet light-absorbing agent with white inorganic particles coated with comprising alkoxysilanes or polysiloxanes to adhere the ultraviolet light-absorbing agent onto the coating composed of alkoxysilanes or polysiloxanes; and then mixing organic pigments with the particles adhered with the ultraviolet light-absorbing agent to form an organic pigment coat on the particles adhered with the ultraviolet light-absorbing agent.
(4) Method of mixing white inorganic particles with alkoxysilanes or polysiloxanes to form a coating composed of alkoxysilanes or polysiloxanes on the surface of the white inorganic particle; and simultaneously adding both organic pigments and the ultraviolet light-absorbing agent to white inorganic particles coated with alkoxysilanes or polysiloxanes to form a organic pigment coat containing the ultraviolet light-absorbing agent on the coating composed of alkoxysilanes or polysiloxanes.
(5) Method of mixing white inorganic particles with alkoxysilanes or polysiloxanes to form a coating composed of alkoxysilanes or polysiloxanes on the surface of the white inorganic particle; mixing organic pigments with the white inorganic particles coated with alkoxysilanes or polysiloxanes to form an organic pigment coat on the coating layer composed of alkoxysilanes or polysiloxanes; and then mixing the obtained composite particles with the ultraviolet light-absorbing agent to adhere the ultraviolet light-absorbing agent onto the surface of the organic pigment coat, i.e., onto the surface of the composite particle.
The mixing of the ultraviolet light-absorbing agent with the respective particles may be conducted by mechanically mixing and stirring the particles with the ultraviolet light-absorbing agent, or by mechanically mixing and stirring the particles and the ultraviolet light-absorbing agent while spraying a solution containing the ultraviolet light-absorbing agent onto the particles. Substantially whole amount of the ultraviolet light-absorbing agent added can be adhered on the surface of the particles.
The amount of the ultraviolet light-absorbing agent added is preferably 0.1 to 20 parts by weight, more preferably 0.1 to 18 parts by weight, still more preferably 0.1 to 15 parts by weight based on 100 parts by weight of the organic pigments adhered.
The coating with alkoxysilanes or polysiloxanes on the surface of the white inorganic particles or on the surface of the white inorganic particles adhered with the ultraviolet light-absorbing agent may be conducted by mechanically mixing and stirring the respective particles with the alkoxysilanes or polysiloxanes, or by mechanically mixing and stirring the respective particles and the alkoxysilanes or polysiloxanes while spraying a solution containing the alkoxysilanes, or the polysiloxanes onto the particles. Substantially whole amount of the alkoxysilanes or polysiloxanes added can be adhered onto the surface of the respective particles.
Meanwhile, a part of the alkoxysilanes adhered may be converted into organosilane compounds obtainable from the alkoxysilanes through the coating step. Even in such a case, the subsequent steps for adhesion of the organic pigments and the ultraviolet light-absorbing agent are not adversely affected.
In order to uniformly coat the surface of the white inorganic particles with the ultraviolet light-absorbing agent as well as the alkoxysilanes or polysiloxanes, it is preferred that the white inorganic particles are previously deaggregated using a crusher or pulverizer.
In the present invention, the mixing and stirring upon coating with the alkoxysilanes or polysiloxanes and upon adhesion with the organic pigments and the ultraviolet light-absorbing agent may be preferably carried out using an apparatus capable of applying a shear force to the powder mixture, especially such an apparatus capable of simultaneously effecting shear action, spatula stroking and compression. Examples of such apparatuses may include wheel-type kneaders, ball-type kneaders, blade-type kneaders, roll-type kneaders or the like. Among these apparatuses, the wheel-type kneaders are preferred to effectively practice the present invention.
Specific examples of the wheel-type kneaders may include edge runners (similar in meaning to mix muller, Simpson mill and sand mill), multi mill, Stotz mill, Wet pan mill, corner mill, ring muller or the like. Among these kneaders, preferred are edge runners, multi mill, Stotz mill, Wet pan mill and ring muller, and more preferred are edge runners. Specific examples of the ball-type kneaders may include vibration mill or the like. Specific examples of the blade-type kneaders may include Henschel mixer, planetary mixer, Nauter mixer or the like. Specific examples of the roll-type kneaders may include extruders or the like.
The conditions of the mixing and stirring treatment may be selected so as to uniformly coat the surface of the white inorganic particle with the alkoxysilane compounds or polysiloxanes. Specifically, the mixing and stirring conditions may be appropriately controlled such that the linear load is usually 19.6 to 1,960 N/cm (2 to 200 Kg/cm), preferably 98 to 1,470 N/cm (10 to 150 Kg/cm), more preferably 147 to 980 N/cm (15 to 100 Kg/cm); the treating time is usually 5 minutes to 24 hours, preferably 10 minutes to 20 hours; and the stirring speed is usually 2 to 2,000 rpm, preferably 5 to 1,000 rpm, more preferably 10 to 800 rpm.
The amount of the alkoxysilanes or polysiloxanes added is preferably 0.15 to 45 parts by weight based on 100 parts by weight of the white inorganic particles. By adding the alkoxysilanes or polysiloxanes in an amount of 0.15 to 45 parts by weight, it is possible to adhere 1 to 200 parts by weight of the organic pigments onto 100 parts by weight of the white inorganic particles.
The amount of the organic pigments added is usually 1 to 200 parts by weight based on 100 parts by weight of the white inorganic particles. When the amount of the organic pigments added is out of the above-specified range, it may be difficult to obtain the aimed organic and inorganic composite pigments.
The organic pigments are preferably added slowly, in particular, for about 5 to 60 minutes.
The organic and inorganic composite pigments obtained after adhesion of the organic pigments may be subjected, if required, to drying or heating treatment.
The heating temperature used in the drying or heating treatment is preferably 40 to 150xc2x0 C., more preferably 60 to 120xc2x0 C., and the heating time is preferably 10 minutes to 12 hours, more preferably 30 minutes to 3 hours.
The alkoxysilanes used for coating the white inorganic particles in the organic and inorganic composite pigments are finally coated in the form of organosilane compounds obtainable from the alkoxysilanes through these treating steps.
The white inorganic particles may be preliminarily coated, if required, with a coat comprising at least one compound selected from the group consisting of hydroxides of aluminum, oxides of aluminum, hydroxides of silicon and oxides of silicon, prior to mixing and stirring with the alkoxysilane compounds or polysiloxanes.
The formation of the intermediate coat may be conducted by adding an aluminum compound, a silicon compound or both the aluminum and silicon compounds to a water suspension containing the white inorganic particles; mixing and stirring the resultant suspension, if required, followed by adequately adjusting the pH value thereof, thereby coating the white inorganic particles with at least one compound selected from the group consisting of hydroxides of aluminum, oxides of aluminum, hydroxides of silicon and oxides of silicon; and then subjecting the thus obtained particles to filtering-out, water-washing, drying and pulverization. Further, if required, the resultant particles may be subjected to deaeration, compaction or the like.
Examples of the aluminum compound may include aluminum salts such as aluminum acetate, aluminum sulfate, aluminum chloride and aluminum nitrate, alkali aluminates such as sodium aluminate, or the like.
Examples of the silicon compound may include water glass #3, sodium orthosilicate, sodium metasilicate or the like.
The point of the present invention is that the organic and inorganic composite pigments of the present invention can exhibit not only a clear hue, but also a more excellent light resistance.
The reason why the organic and inorganic composite pigments of the present invention can exhibit a clear hue, is considered by the present inventors to be that the organic pigments having a clear hue are adhered onto the surface of the white inorganic particles, and prevented from being desorbed therefrom.
The reason why the organic pigments adhered to the organic and inorganic composite pigments can be prevented from being desorbed from the surface of the organic and inorganic composite pigments, is considered by the present inventors to be that the white inorganic particles and the organic pigment coat are strongly bonded to each other through the coating comprising organosilane compounds obtainable from alkoxysilanes, or polysiloxanes.
Further, in the organic and inorganic composite pigments of the present invention, the ultraviolet light-absorbing agent is caused to exist inside and/or on the organic and inorganic composite particles. Therefore, the organic and inorganic composite pigments are free from discoloration due to exposure to ultraviolet light and can exhibit a more excellent light resistance.
Another point of the present invention is that the paint containing the organic and inorganic composite pigments is excellent in light resistance, paint stability and dispersibility, and the resin composition containing the organic and inorganic composite pigments is excellent in light resistance and dispersibility.
The reason why the paint and resin composition of the present invention can exhibit an excellent light resistance, is considered by the present inventors to be that the organic and inorganic composite pigments contained therein are excellent in light resistance. Also, the reasons why the paint of the present invention can exhibit excellent paint stability and dispersibility, and the resin composition of the present invention can exhibit an excellent dispersibility, are considered by the present inventors to be that the paint and resin composition contain as colorant, the organic and inorganic composite pigments whose organic pigments are prevented from being desorbed from the surface of the organic and inorganic composite particles.
In addition, the organic and inorganic composite pigments of the present invention contain no harmful elements and compounds and, therefore, can provide pigments having excellent hygiene and safety and being free from environmental pollution.
Thus, the organic and inorganic composite pigments of the present invention are not only substantially free from desorption of organic pigments from the surface of the organic and inorganic composite particles, but also can exhibit a more excellent light resistance due to the ultraviolet light-absorbing agent contained therein and/or adhered thereon. Therefore, the organic and inorganic composite pigments of the present invention can be suitably used as a colorant in various applications.
The paint and resin composition of the present invention contain as color pigments, the organic and inorganic composite pigments being substantially free from desorption of organic pigments therefrom and exhibiting a more excellent light resistance and, therefore, are suitable as paints and resin compositions having a more excellent light resistance.